Department of Fisheries Science, Chonnam National University, Yeosu 59626, Republic of Korea.
Ocean and Fisheries Science Institute, Jeollanam-do 59326, Republic of Korea.
Int J Mol Sci. 2023 May 17;24(10):8919. doi: 10.3390/ijms24108919.
The seed production of small yellow croaker (SYC) is constrained by reproductive dysfunction in captive-reared females. Reproductive dysfunction is closely linked to endocrine reproductive mechanisms. To better understand the reproductive dysfunction in captive broodstock, functional characterization of gonadotropins (GtHs: follicle stimulating hormone β subunit, luteinizing hormone β subunit, and glycoprotein α subunit, ) and sex steroids (17β-estradiol, E2; testosterone, T; progesterone; P) was performed using qRT-PCR, ELISA, in vivo, and in-vitro assay. The pituitary GtHs and gonadal steroids levels were significantly higher in ripen fish of both sexes. However, changes in and E2 levels in females were not significant in the developing and ripen stages. Furthermore, GtHs and steroids levels were lower in females compared to males throughout the reproductive cycle. In vivo administration of gonadotropin releasing hormone analogue (GnRHa) significantly increased the expression of GtHs in both dose- and time-related manners. The lower and higher doses of GnRHa led to successful spawning in male and female SYC, respectively. Sex steroids in vitro significantly inhibited the expression of in female SYC. Overall, GtHs were shown to play a vital role in final gonadal maturation, while steroids promoted negative feedback in the regulation of pituitary GtHs. Lower levels of GtHs and steroids might be key components in the reproductive dysfunction of captive-reared female SYC.
小黄鱼（SYC）的种子生产受到人工养殖雌鱼生殖功能障碍的限制。生殖功能障碍与内分泌生殖机制密切相关。为了更好地理解人工养殖亲鱼的生殖功能障碍，使用 qRT-PCR、ELISA、体内和体外测定法对促性腺激素（GtHs：卵泡刺激素β亚基、黄体生成素β亚基和糖蛋白α亚基）和性类固醇（17β-雌二醇，E2；睾丸激素，T；孕酮；P）进行了功能表征。在两性成熟鱼中，垂体 GtHs 和性腺类固醇水平显著升高。然而，在发育和成熟阶段，E2 水平在雌鱼中的变化并不显著。此外，在整个生殖周期中，雌鱼的 GtHs 和类固醇水平均低于雄鱼。体内给予促性腺激素释放激素类似物（GnRHa）后，GtHs 的表达在剂量和时间相关的方式下均显著增加。GnRHa 的低剂量和高剂量分别导致雄性和雌性 SYC 成功产卵。体外性类固醇显著抑制了雌性 SYC 中 基因的表达。总的来说，GtHs 在最终性腺成熟中起关键作用，而类固醇在调节垂体 GtHs 方面起负反馈作用。GtHs 和类固醇水平较低可能是人工养殖雌鱼生殖功能障碍的关键因素。
